The harmful effects of ultraviolet radiation from sunlight are well documented. The major short-term hazard of exposure to ultraviolet radiation is sunburn, which is caused primarily by ultraviolet radiation of wavelengths between 290 to 320 nanometers (UVB radiation). Ultraviolet radiation in the wavelength range of 320 to 400 nanometers (UVA radiation) also contributes to sunburn. Long term hazards of ultraviolet radiation exposure include malignant changes in the skin surface leading to skin cancer and premature aging of the skin.
Sunscreens are well known and frequently used personal care products designed to protect the skin from the harmful effects of ultraviolet radiation from the sun. These sunscreen products contain sunscreen agents which absorb or scatter harmful ultraviolet radiation. The problem with current sunscreen products is that they are easily rubbed off or washed off by perspiration or swimming. Consequently, frequent reapplication is required to maintain protection. To address the lack of durability of sunscreen products, polymers, heavy waxes and oils are added to the compositions to impart water resistance (for example, Woodin et al., U.S. Pat. No. 5,219,558). However, the use of these additives has not been entirely successful. A long-lasting, durable sunscreen with improved water resistance would represent an advance in the art.
In order to improve the durability of hair and skin care products, peptide-based hair conditioners, hair colorants, and other benefit agents have been developed (Huang et al., copending and commonly owned U.S. Patent Application Publication No.2005/0050656, and U.S. Patent Application Publication No. 2005/0226839). The peptide-based conditioners or colorants are prepared by coupling a specific peptide sequence that has a high binding affinity to hair or skin with a conditioning or coloring agent, respectively. The peptide portion binds to the hair or skin, thereby strongly attaching the conditioning or coloring agent. Additionally, peptide-based inorganic sunscreens comprising a skin-binding peptide coupled to an inorganic metal oxide sunscreen agent are described by Buseman-Williams et al. (copending and commonly owned U.S. Patent Application Publication No. 2005/0249682). However, sunscreens formed by coupling a skin-binding peptide to an organic sunscreen agent have not been described.
Peptides having a binding affinity to hair and skin have been identified using phage display screening techniques (Huang et al., supra; Estell et al. WO 0179479; Murray et al., U.S. Patent Application Publication No. 2002/0098524; Janssen et al., U.S. Patent Application Publication No. 2003/0152976; and Janssen et al., WO 04048399). Additionally, empirically generated hair and skin-binding peptides that are based on positively charged amino acids have been reported (Rothe et., WO 2004/000257).
In view of the above, a need exists for organic sunscreens that provide improved durability for long lasting effects and are easy and inexpensive to prepare.
Applicants have addressed the stated need by designing peptide-based organic sunscreens formed by coupling skin-binding peptides, which bind to skin with high affinity, to organic sunscreen agents to give sunscreens that provide long lasting protection.